JP2014508709A - Polysilanesiloxane copolymer and method for converting to silicon dioxide - Google Patents

Abstract

Inorganic polysilane siloxane (PSSX) copolymers and methods for making and applying inorganic polysilane siloxane (PSSX) copolymers on a substrate surface are provided. This PSSX copolymer is beneficial for forming a dense silicon dioxide layer on a substrate under mild oxidizing conditions. PSSX copolymers contain Si _x O _y (OH) _z , where y and z are defined by the relationship (2y + z) ≦ (2x + 2), where x is either 4 or 5. More particularly, PSSX copolymers do not contain Si-C covalent bonds.

Description

  The present disclosure relates generally to inorganic polysilane-polysiloxane resins and their use in electronic devices. More particularly, the present disclosure describes the preparation of polysilane siloxane (PSSX) copolymers and methods of using these copolymers to form spin-on films that can be converted to a dense silicon dioxide layer under mild conditions. , Regarding.

High density silicon dioxide (SiO ₂ ) layers are typically used in electronic devices as dielectrics or barrier materials. These dense layers can be formed using either a chemical vapor deposition (CVD) process or a spin-on deposition (SOD) process. In the CVD process, volatile precursors are reacted in the gas phase such that silicon dioxide is deposited directly on the surface of the electronic device. Alternatively, the SOD process includes applying a resinous precursor to the surface of the electronic device. These resinous precursors form a film on the surface, which is subsequently oxidized to form silicon dioxide. The use of the SOD process provides several advantages over the CVD process, including lower cost and the ability to cover gaps formed in complex patterns.

Organopolysilanesiloxane (PSSX) represents a class of copolymers that include a hybrid of polysilane units and polysiloxane units. The PSSX copolymer may be essentially linear or resinous. Linear PSSX copolymers are conventionally obtained via hydrolytic polycondensation of dichlorooligosilanes such as Cl (SiMe ₂ ) ₆ Cl as described in US Pat. No. 4,618,666, US Pat. 946, via polycondensation that occurs between dichloro-oligosilane and oligosilanediol, such as, for example, between Cl (SiMe ₂ ) ₆ Cl and HO (SiMe ₂ ) ₆ OH, or Japan It is synthesized via ring-opening polymerization (ROP) of cyclic silaethers such as (SiMe ₂ ) ₄ O as described in published patent application H04-0665427. Resinous PSSX copolymers are conventionally synthesized via hydrolysis condensation of chloromethyldisilane formed as a direct process residue (DPR) or byproduct in the production of dichlorodimethylsilane. A more complete description of the composition, synthesis, properties, and applications related to polysilanesiloxane (PSSX) copolymers was published by Polymer and Consolidating Polysiloxane Blocks, Wiley, New York, (1973), pages 305-53 by Plumb and Atherton. Manuscripts and Chojnowski, et al. Can be found in the article published in Progress in Polymer Science, 28 (5), (2003), pages 691-728.

Organic PSSX copolymers contain a substantial number of organic functional moieties. In other words, the organic PSSX copolymer contains a substantial number of Si-C bonds. In order to form a silicon dioxide (SiO ₂ ) layer, it is necessary to remove these organic portions. Unfortunately, removal of these organic groups results in undesirably high weight loss, large shrinkage, and formation of gaps in the formed silicon dioxide layer. Therefore, organic PSSX copolymers are not suitable or desirable precursors for making high density silicon dioxide layers in electronic devices.

To overcome the shortcomings and other limitations of the related arts listed, the present disclosure provides inorganic polysilane siloxane (PSSX) copolymers that are used to form a silicon dioxide layer on a substrate. PSSX copolymer is defined as Si _x O _y (OH) _z , where y and z are defined by the relationship (2y + z) ≦ (2x + 2), where y and z are numbers greater than or equal to 0, x Are units of either 4 or 5. More particularly, PSSX copolymers do not contain Si-C covalent bonds.

According to one aspect of the present disclosure, a polysilanesiloxane (PSSX) copolymer is prepared by mixing a predetermined number of monomers in a protic solvent such as an alcohol and hydrolyzing under controllable conditions to form a PSSX polymer. Provide a method. Hydrolysis is preferably facilitated by using excess acidic water in a protic solvent. The monomer is selected from the group of peralkoxyoligosilanes, alkoxychlorooligosilanes, and mixtures thereof. Some examples of these monomers include Si [Si (OMe) ₃ ] ₄ , Si [Si (OMe) ₃ ] ₃ [Si (OMe) ₂ Cl], HSi [Si (OMe) ₃ ] ₃ , and Examples thereof include, but are not limited to, and Me represents a methyl group.

The alkoxychloro oligomer preferably used in the present disclosure has the general formula: H _w Si _x (OR) _y Cl _z (wherein R is an alkyl group such as ethyl or methyl group; w is 0 or 1 X is either 4 or 5; y and z are numbers greater than or equal to 0, and (y + z) is equal to (2x + 2) when w = 0 and x = 5, or w = 1 and x = 4 (y + z) = 9).

  According to another aspect of the present disclosure, a method of forming a silicon dioxide layer on a substrate using a PSSX copolymer as described above is provided. In this method, a PSSX copolymer is applied to a substrate such as an electronic device to form a PSSX film. More particularly, the PSSX copolymer is applied to the substrate by spin coating, flow coating, or dip coating. The PSSX copolymer may be applied to the substrate, even in the protic or hydrolytic solvent used to prepare the copolymer. Optionally, the protic solvent may be replaced with another film-forming solvent such as propylene glycol monomethyl ether acetate (PGMEA) before applying the PSSX copolymer to the substrate.

  The PSSX film is gently oxidized to form a silicon dioxide layer on the substrate. The oxidation process typically includes exposing the PSSX film to one selected from the group of steam or oxygen gas and heating the film to less than about 600 ° C. for a predetermined time. Optionally, the method may further comprise annealing the silicon dioxide layer under an inert atmosphere such as nitrogen gas to increase the density of the layer. This silicon dioxide layer may be used as a dielectric or barrier material in electronic devices.

  Further scope of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.

The drawings described herein are for illustrative purposes only and are not intended to limit in any way the scope of the present disclosure.
1A-1H are schematic representations of formulas related to several different peralkoxy oligosilane or alkoxy chloro oligo silane monomers that can be used in the preparation of PSSX copolymers in accordance with the teachings of this disclosure. 1 is a schematic illustration of the methods used to prepare PSSX copolymer, form a PSSX film on a substrate, and convert the film to a silicon dioxide layer according to one aspect of the present disclosure. 1 is a graphical representation of an absorption spectrum measured by Fourier transform infrared (FTIR) spectroscopy for a silicon dioxide layer made by oxidation of a PSSX film according to one embodiment of the present disclosure. 2 is a graphical representation of an elution profile obtained by gel permeation chromatography (GPC) of a PSSX copolymer prepared according to one embodiment of the present disclosure.

  The following description is merely exemplary in nature and is in no way intended to limit the present disclosure or its application or use. It should be understood that throughout the description and drawings, corresponding reference numerals indicate like or corresponding parts and features.

  The present disclosure generally provides inorganic polysilane siloxane (PSSX) copolymers or resins that do not contain Si-C bonds, and methods of making them. The present disclosure further provides a method of applying a PSSX copolymer on a substrate to form a PSSX film, and a method of exposing the PSSX film to a mild oxidative cure that can convert the film into a dense silicon dioxide layer.

  The density of the silicon dioxide layer formed from the oxidative transformation of a film containing the inorganic PSSX copolymer of the present disclosure benefits from the absence of Si-C in the PSSX copolymer. The density of the silicon dioxide layer formed from the inorganic PSSX copolymer also has a 28% mass increase and about 11% local volume increase by converting one Si-Si bond to one Si-O-Si bond. Have the benefit to be brought. In addition, Si—Si bonds are reactive to oxidation and can be easily converted to Si—O—Si bonds under mild conditions, such as at relatively low temperatures. Therefore, using these inorganic PSSX copolymers to form high density silicon dioxide films can provide the benefits of reducing the costs associated with manufacturing electronic devices.

Inorganic PSSX copolymers are prepared according to the teachings of the present disclosure via controlled hydrolysis of peralkoxyoligosilane monomers, alkoxychlorooligosilane monomers, or mixtures thereof. According to one aspect of the present disclosure, the peralkoxyoligosilane and alkoxychlorooligosilane monomers have a composition represented by the general formula shown in (I).
H _w Si _x (OR) _y Cl _z (I)
Wherein R is an alkyl group, preferably a methyl (Me) or ethyl (Et) group; w is either 0 or 1; x is either 4 or 5. Y and z are numbers greater than or equal to 0 as defined by the relationship (y + z) = (2x + 2) when w = 0 and x = 5; or (y + z) = 9 when w = 1 and x = 4 ) Referring now to FIG. 1, formulas A-H, examples of these monomers include Si [Si (OMe) ₃ ] ₄ (1A), Si [Si (OMe) ₃ ] ₃ [Si (OMe), among others. ) ₂ Cl] (1B), HSi [Si (OMe) ₃ ] ₃ (1C), Si [Si (OEt) ₃ ] ₄ (1D), Si [Si (OEt) ₃ ] ₃ [Si (OEt) ₂ Cl ] (1E), HSi [Si (OEt) ₃ ] ₃ (1F), Si [Si (OEt) ₃ ] ₂ [Si (OEt) ₂ Cl] ₂ (1G) and Si [Si (OEt) ₃ ] [Si (OEt) ₂ Cl] ₃ (1H), but are not limited to these. As used herein, Me and Et refer to methyl and ethyl groups, respectively. Monomers may be prepared as the main product or may be produced as a by-product derived from alkoxylation of perchloroneopentasilane, Si (SiCl ₃ ) ₄ and alcohol. The alkoxylation of Si (SiCl ₃ ) ₄ is carried out in a way that makes the desired monomer the dominant product of the reaction.

These monomers may be used to form inorganic polysilanesiloxane (PSSX) copolymers. PSSX copolymers are generally Si _x O _y (OH) _z , where y and z are numbers greater than or equal to 0 as defined by the relationship (2y + z) ≦ (2x + 2), where x is either 4 or 5 Unit). In particular, x is 5 if desired. PSSX copolymers prepared in accordance with the teachings of this disclosure do not contain Si—C covalent bonds. However, those skilled in the art will appreciate that PSSX copolymers can contain small amounts of Si-C bonds, if derived from impurities or desired, without exceeding the scope of the present disclosure.

  Referring now to FIG. 2, method (1) of preparing a PSSX copolymer according to one aspect of the present disclosure includes a step (5) of providing a peralkoxyoligosilane or alkoxychlorooligosilane monomer, and the monomer as a protic solvent such as an alcohol. Mixing in to form a reaction mixture (10). The monomers in the reaction mixture are then hydrolyzed under predetermined and controllable conditions to form (15) PSSX copolymer. These monomers may be hydrolyzed in protic solvents by using an excess amount of acidic water present in the solvent.

  Still referring to FIG. 2, a method (2) of forming a high density silicon dioxide layer using a PSSX copolymer or resin as prepared in a protic hydrolysis solvent is shown. In this method (2), a substrate is first supplied (20). This substrate is preferably an electronic device. However, those skilled in the art have described PSSX copolymers made and used in accordance with the teachings contained herein, in conjunction with the formation of high density dielectric or barrier layers in electronic devices to illustrate the system and method of use. You will understand that It is envisioned that it is within the scope of this disclosure to incorporate and use such PSSX copolymers to form silicon dioxide layers on other substrates.

A PSSX copolymer may be applied to the surface of the substrate (25) to form a PSSX film. Alternatively, prior to applying the PSSX copolymer to the surface of the substrate, the protic solvent may be exchanged with other conventional film-forming solvents such as propylene glycol monomethyl ether acetate (PGMEA) (30). Optimize monomer concentration, solvent, acidity, SiOMe: H ₂ O molar ratio, reaction time, solvent exchange procedure, and other reaction conditions to create stable PSSX copolymers that exhibit outstanding thin film-forming properties be able to. The PSSX copolymer may be applied to the surface of the substrate using any conventional technique known to those skilled in the art including, but not limited to, spin coating, flow coating, and dip coating. For example, the inorganic PSSX resin may be deposited on a silicon wafer substrate by a standard spin coating procedure that includes about 20 seconds at a static rotational speed of about 2000 rpm to form a defect-free film.

The PSSX film is finally oxidized (35) to convert it to a dense silicon dioxide layer. For example, the film may be gently baked on a hot plate and cured in a furnace under mild oxidizing conditions for a predetermined time. Referring now to FIG. 3, the PSSX film can be converted to silicon dioxide at a temperature of 400 ° C. or higher in the presence of steam or oxygen. The mildness of the oxidative condition is indicated by the formation of a relatively thin oxide layer on the silicon substrate, for example about 19 mm. The FTIR spectrum collected after vapor curing at 550 ° C. shows strong infrared absorption associated with silicon dioxide at about 1080, 800, and 460 cm ⁻¹ . Those skilled in the art, with the strongest absorption of approximately 1080 cm ^-1 is due to expansion and contraction of the Si-O bond in the silicon dioxide, each weaker absorption of about 800 and about 460 cm ^-1, O-Si- in the silicon dioxide It will be understood that this is caused by the bending modes associated with O and Si-O-Si bonds.

  Optionally, the density of the silicon dioxide layer may be further increased by exposure to high temperature annealing (40) under an inert atmosphere such as nitrogen. Such further densification of silicon dioxide makes the layer resistant to etching with hydrofluoric acid. For example, a PSSX film and a conventional hydrogen silsesquioxane (HSQ) film are applied to the same substrate, and under similar conditions, in steam at 550 ° C. for 30 minutes and in nitrogen at 850 ° C. for 30 minutes. Oxidized or cured. The silicon dioxide layer obtained from the PSSX film exhibited an etch rate of 76 Å / min when exposed to a diluted 100: 1 HF etchant. In comparison, this etch rate was observed to be much lower than the 125 Å / min etch rate measured on the silicon dioxide layer obtained from the HSQ film (control).

  The following specific examples are provided to illustrate the invention and should not be construed to limit the scope of the invention.

Example 1 Preparation of Monomer In this example, 261 grams of Si (SiCl ₃ ) ₄ dissolved in 1033 grams of toluene was mixed with 448 ml of methanol. All low boiling byproducts were removed from the reaction mixture and a total of 209 grams of the methoxylated crude product was isolated. The crude product was remixed in 1154 ml of methanol for a predetermined time to purify the product. After removing the methanol, a total of 206 g of high purity Si [Si (OMe) ₃ ] ₄ was recovered. The resulting purity of the monomer, Si [Si (OMe) ₃ ] ₄ from this reaction was over 90% and the total yield was about 87%. The structure and purity of the product was confirmed using gas chromatography (GC), gas chromatography-mass spectrometry (GC-MS), nuclear magnetic resonance (NMR), Raman spectroscopy, and UV-Vis spectroscopy. . One skilled in the art will understand that GC, GC-MS, NMR, Raman, and UV-Vis are common techniques used to confirm the composition and purity of materials prepared in chemical reactions. I will.

Example 2-Preparation of PSSX Copolymer In this example, 16.66 grams of Si [Si (OMe) ₃ ] ₄ was used with 10.55 grams of 0.1N HCl, a molar ratio of SiOMe: H ₂ O of 1 At 1.5: hydrolyzed in 70.37 grams of ethanol at room temperature for 3 hours to form a PSSX copolymer. Then 138.22 grams of PGMEA was added and the solution was concentrated to 51.20 grams to obtain a stable 15 wt% resin solution. Referring now to FIG. 4, it has been shown that PSSX copolymers in PGMEA solvent are separated by gel permeation chromatography (GPC) within an elution time of about 15.5 to 19.0 minutes. One skilled in the art will appreciate that the measured GPC detector response can be converted to weight fractions and that the elution time can be converted to a molecular weight scale by accurate calibration of the instrument. The PSSX copolymer prepared in this example exhibits a number average molecular weight (M _n ) on the order of about 1500 amu and a weight average molecular weight (M _w ) of about 3500 amu.

While not wishing to be bound by theory, the SiSi ₄ units remain unchanged in the copolymer or resin as determined by interpretation of measured ²⁹ Si NMR data (not shown). Conceivable. In this example, a PSSX copolymer prepared in accordance with the teachings of this disclosure is [Si ₅ O _x (OH) _y (OMe) _z ] _n , where x, y, and z are numbers greater than or equal to zero; (The sum of (2x + y + z) is equal to 12). Because this resin has a high silanol concentration, it may be stored, for example, at −15 ° C. in a freezer, and the resin will remain stable for a long period of time, ie, exhibit a long shelf life.

  One skilled in the art will recognize that the measurements described are standard measurements that can be obtained by a variety of different test methods. The test methods described in the examples represent only one method that can be used to obtain each of the required measurements.

  The foregoing descriptions of various embodiments of the present invention have been presented for purposes of illustration and description. This description is not exhaustive or is intended to limit the invention to the precise embodiments disclosed. Many modifications or variations are possible in light of the above teaching. The discussed embodiments have been selected and described to provide the best description of the principles of the invention and its practical application, so that those skilled in the art can make various modifications suitable for the particular use envisioned, The present invention can be used in various embodiments. All such modifications and changes are intended to be within the scope of the present invention as determined by the appended claims when they are interpreted fairly, legally and fairly according to the extent to which they are entitled. include.

Claims (16)

A polysilanesiloxane (PSSX) copolymer used in forming a silicon dioxide layer on a substrate, wherein the PSSX copolymer is Si _x O _y (OH) _z , wherein y and z are (2y + z) ≦ (A number greater than or equal to 0 as defined by the relationship (2x + 2), where x is either 4 or 5.) Polysilanesiloxane copolymer comprising units.   The polysilanesiloxane copolymer according to claim 1, wherein x is 5.   The polysilanesiloxane copolymer according to claim 1 or 2, wherein the PSSX copolymer does not contain a Si-C covalent bond. A process for preparing a polysilanesiloxane (PSSX) copolymer comprising:
Supplying a predetermined number of monomers selected from the group of peralkoxy oligosilanes, alkoxychlorooligosilanes, and mixtures thereof;
Mixing the monomers in a protic solvent to form a reaction mixture;
Hydrolyzing the monomer in the reaction mixture to form a PSSX copolymer;
Including a method. Said step of supplying a predetermined number of peralkoxyoligosilane or alkoxychlorooligosilane monomers has the general formula:
H _w Si _x (OR) _y Cl _z
(Wherein, R is an alkyl group, w is either 0 or 1, x is either 4 or 5, y and z are 0 or more, and w = Use of monomers having (y + z) = (2x + 2) when 0 and x = 5, or (y + z) = 9 when w = 1 and x = 4). the method of.   The method according to claim 5, wherein R is one selected from the group of a methyl group and an ethyl group. The monomer is 1 from the group of Si [Si (OMe) ₃ ] ₄ , Si [Si (OMe) ₃ ] ₃ [Si (OMe) ₂ Cl], HSi [Si (OMe) ₃ ] ₃ , and mixtures thereof. The method according to any one of claims 4 to 6, wherein one is selected.   The method according to any one of claims 4 to 7, wherein the step of hydrolyzing the monomer in the reaction mixture uses an excess of acidic water present in the protic solvent.   9. The process of any one of claims 4 to 8, wherein the step of mixing the monomer into a protic solvent uses a protic solvent selected from the group of methyl alcohol, ethyl alcohol, and isopropyl alcohol. the method of.   The method according to any one of claims 4 to 9, further comprising the step of replacing the protic solvent with a film-forming solvent. A method for preparing a silicon dioxide layer on a substrate, comprising:
Preparing a polysilanesiloxane (PSSX) copolymer according to any one of claims 4-10;
Supplying a substrate;
Applying the PSSX copolymer to the substrate to form a PSSX film;
Oxidizing the PSSX film to form a silicon dioxide layer;
Including a method. Oxidizing the PSSX film to form a silicon dioxide layer;
Exposing the PSSX film to one selected from the group of steam or oxygen gas;
Heating the PSSX film for less than about 600 ° C. for a predetermined time;
The method of claim 11, wherein an oxidation process comprising:   The method according to claim 11 or 12, further comprising annealing the silicon dioxide layer for a predetermined time under an inert atmosphere.   14. The method according to any one of claims 11 to 13, wherein the step of applying the PSSX copolymer to a substrate uses a method selected from the group of spin coating, flow coating and dip coating.   A silicon dioxide layer used as a dielectric or barrier material in an electronic device, wherein the silicon dioxide layer is prepared according to the method of any one of claims 11-14. 15. An electronic device, the electronic device comprising a substrate and a silicon dioxide layer in contact with the substrate, wherein the silicon dioxide layer is prepared according to the method of any one of claims 11-14. And
An electronic device wherein the silicon dioxide layer has a density sufficient to be used as a dielectric or barrier material.

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